U.S. President Donald Trump meets with Russian Foreign Minister Sergey Lavrov, left, next to Russian Ambassador to the U.S. Sergei Kislyak at the White House in Washington, Wednesday, May 10, 2017. Trump on Wednesday welcomed Vladimir Putin's top diplomat to the White House for Trump's highest level face-to-face contact with a Russian government official since he took office in January. (Russian Foreign Ministry Photo via AP)

President Donald Trump described ex-FBI Director James Comey as a "nut job" before insisting his firing would relieve "great pressure," according to a memo read aloud to The New York Times.

The Times recounted the May 10 meeting between Trump and Russian officials foreign minister Sergey Lavrov and ambassador Sergey Kislyak. Per The Times report:

“I just fired the head of the F.B.I. He was crazy, a real nut job,” Mr. Trump said, according to the document, which was read to The New York Times by an American official. “I faced great pressure because of Russia. That’s taken off.”

White House press secretary Sean Spicer did not refute the details of the memo to The Times.

The developments were a blow to White House efforts to tamp down interest in the Russia investigation as Trump and his staff boarded Air Force One for Saudi Arabia, first stop on his first foreign trip as president. The details of his comments to the Russians would seem to bolster theories that Trump fired Comey in an effort to choke off the Russia investigation.

Earlier this week, the Justice Department appointed former FBI Director Robert Mueller to take over the federal investigation in an effort to re-establish independence from the White House.